From success, you learn absolutely nothing. From failure and setbacks conclusions can be drawn. That goes for your private life as well as your career.
I was not interested at all in Formula One when I left; I was very busy with my airline. But slowly I started missing the adrenaline rush and the driving of such fantastic cars at the limit. In reality this urge never disappears when you're a top driver, because I think we're a different breed of people, we need to take chances, we need to push ourselves to the limit all the time, that sort of thing. It stays with you, although you can kill it by losing motivation or other things in your life, but it never leaves you forever.
In Germany air became generally accepted Berlin in this area. It operated with 45 airplanes within the Low Cost range from Germany, and is one the most successful carriers in Europe.
It was the same with Schumacher: the need for the adrenaline rush, to push himself to the limit was always there. So without a Formula One car to race with he went on to do motorcycle racing and other stupid things, and obviously that wasn't enough to keep him happy, so he had a problem to sort out and returning to racing was his answer to the problem.